Process for the production of active anhydrous aluminum chloride

ABSTRACT

Aromatic ketocarboxylic acids represented by the formula,   WHEREIN R1 and R2 are individually hydrogen, chlorine, or a straight or branched lower alkyl or a substituted or unsubstituted cycloalkyl, are prepared by reacting phthalic anhydride with a compound represented by the formula,   WHEREIN R1 and R2 are as defined above, in the presence of a specific aluminum chloride catalyst. The specific aluminum chloride is prepared by reacting metallic aluminum with anhydrous hydrogen chloride using at least one member of trihalogenated benzenes as a solvent.

United States Patent [191 Suda et al.

[ Oct. 9, 1973 PROCESS FOR THE PRODUCTION OF ACTIVE ANI-IYDROUS ALUMINUMCHLORIDE [21] Appl. No.: 153,029

[30] Foreign Application Priority Data June 19, 1970 Japan... 45/53649Apr. 21, 1971 Japan 46/26259 [52] US. Cl 423/495, 423/131, 260/517 [51]Int. Cl. COII 7/58 [58] Field of Search 423/126, 495, 135, 423/136, 496,131; 252/364 [56] References Cited UNITED STATES PATENTS 2,057,30610/1936 Martin et'al. 423/496 3,627,483 12/1971 Cole et al. 423/1353,651,159 3/1972 Long et al 423/495 X 2,846,290 8/1958 Yacoe 423/485FOREIGN PATENTS OR APPLICATIONS 901,166 7/1962 Great Britain 423/495Primary Examiner- Edward Stern Attorney-Stevens et a1.

[57} ABSTRACT Aromatic ketocarboxylic acids represented by the formula,

COOH

wherein R, and R are individually hydrogen, chlorine, or a straight orbranched lower alkyl or a substituted or unsubstituted cycloalkyl, areprepared by reacting phthalic anhydride with a compound represented bythe formula,

metallic aluminum with anhydrous hydrogen chlorideusing at least onemember of trihalogenated benzenes as a solvent.

2 Claims, No Drawings PROCESS FOR THE PRODUCTION OF'ACTI'VE ANI-IYDROUSALUMINUM CHLORIDE This invention relates to a process for preparingaromatic ketocarboxylic acids and more particularly to a novel processfor preparing o-benzoylbenzoic acids,

and to a process for preparing active anhydrous aluminum chloride.

It is well known that anthraquinone derivatives, which are veryimportant intermediates for the production of various dyes and pigments,are prepared from the most active catalyst for the preparation ofobenzoylbenzoic acids.

An object of the present invention is to provide a novel process forpreparing o-benzoylbenzoic acids in. high yield and in highpurity usingthe specific'alumi? num chloride-catalyst. Another object of: thepresent invention is to provide a novel process for preparingobenzoylbenzoic acids in a shorter reactiontime.

A further object of the present invention is'to provide a process forthe production of such a specific alumi-. num chloride.

The present invention, therefore,- provides a process for thepreparation of aromatic ketocarboxylic-acids represented by the formula,

wherein R and R are individually hydrogen, chlorine, or a straight orbranched lower alkyl such as methyl, ethyl, n-propyl, iso-propyl,n-butyl, iso-butyl, sec-bu'tyl, t-butyl, substituted or unsubstitutedcycloalkyl such as cyclohexyl and the like, which comprises reactingphthalic anhydride with a benzene derivative reprerente y iaamalstm.

wherein R and R are as defined above, in the presence of anhydrousaluminum chloride prepared by reacting metallic aluminum with anhydroushydrogen chloride using at least one member of trihalogenated. benzenesas a solvent.

In carrying out the present process, examples of-benzene derivativesrepresented by the formula.(ll) are benzene, monochlorobenzene, toluene,ethylbenzene and the like. It is advantageous to employ 2.0-20.0 molesof the compounds (ll) per mole of phthalic anhydride. The preferablemolar ratio depends on other reaction factors such as viscosity of thereaction system,

and thelike.

Temperatures between 0 and 100 C, preferably 10 to C may be employed insaid reaction.

As to other reaction conditions, those of conventional processes may beapplied in the present reaction.

The anhydrous aluminum chloride prepared according to the presentprocess, which is explained in more detail later, is used in anamount of2.0 to 3.0 moles, preferably 2.1- to 2.4 moles per mole of phthalicanhydride.

As=for after-treatment'of the reaction product, ordinary treatments suchas hydrolysis with water followed by extraction of an organic layer withan aqueous alkali solution andprecipitation with acids, or steamdistillation may be employed. According to the present invention thereaction products are obtained in high purity with almostquantitativeyield, so that they may be used without any treatment-for the subsequentsteps.

Asthe specific anhydrous-aluminum chloride is used in the presentinvention, the product can be obtained in; such a remarkably short timeas about l/2-l/3 of that inconventional processes.

Thus, the-present invention provides also a process for the productionof active anhydrous aluminum chloride, which comprises reactingmetallic'aluminum with anhydrous hydrogen chloride using at least onemember of trihalogenated benzenes as a solvent.

It is well .known that anhydrous aluminum chloride is averyimportantindustrial raw material, especially as a catalyst in the Friedel-Craftsreactions, etc.

Anhydrous aluminum chloride has been prepared mostly at high tmperaturesby,

i; reacting metallic aluminum with gaseous chlorine,

ii. reacting metallic aluminum with gaseous hydrogen chloride. Both the(i) and (ii ).pr0cesses, however, have many troubles not only in thereaction itself but in the used apparatus, because the reaction mustbe'carried outzat high temperatures and is a complete gas-solid reaction,and moreover the product sublimes and is corrosive.

It has been proposed to react metallic aluminum with hydrogen chloridein a solvent such as alkylbenzenes which canproduce a complex with theformed anhydrous aluminum chloride. But the complex obtained is used foronly limited reactions.

It is also proposed in US. Pat. No. 2,871,244 to prepare a complex ofaluminum chloride in an aromatic solvent, but the complex obtainedincludes undesirable unknown compounds having low boiling points andresinous materials-which-are caused by transformation of the solvent.

The present inventors have investigated on various solvents used in thereaction between metallic aluminum and hydrogen chloride, and have foundthat the more active anhydrous aluminum chloride is obtained by usingtrihalogenated benzenes as a solvent without producing undesirableunknown compounds and resinous materials mentioned above, because ofalmost negligible transformation of said solvent, and of no forma-' tionof any complex to give free anhydrous aluminum chloride.

As the metallic aluminum, such forms as powders,

ful.

Trihalogenated benzenes such as trichlorobenzene are used in an amountof 5 to 30 times the weight of the aluminum used. The trihalogenatedbenzenes used in the present process include one of their isomers, and amixture of two or more isomers. There may be used socalled industrialtrichlorobenzene containing small amount of more highly chlorinatedbenzenes of dichlorobenzenes.

The reaction is carried out at an elevated temperature, e.g., 30200 C,preferably at 30l50 C.

Addition of a minute amount of aluminum chloride to a solvent prior tothe reaction is preferable.

Hydrogen chloride is supplied to the reaction system until the metallicaluminum is completely consumed, whereby highly activated anhydrousaluminum chloride is almost quantitatively obtained.

The highly activated aluminum chloride obtained disperses uniformly inthe solvent without forming any complex with trihalogenated benzenes, sothat it is used as a catalyst with or without ordinary after-treatment.A part or all of the recovered solvent may be used in the subsequentreaction.

The anhydrous aluminum chloride prepared by the above-mentioned methodsis highly active as a catalyst not only in the preparation ofo-benzoylbenzoic acids but in the ordinary alkylation, Friedel-Craftsreactions including acylation, Fries reaction, Hauben-l-loesch reactionand other condensation reactions.

Thus, the highly activated aluminumchloride can be prepared at a lowercost than any other known processes; therefore, the process of thepresent invention is extremely useful and economical for an industrialproduction.

The following examples will serve furtherto illustrate the presentinvention. It is needless to say that the present invention is notlimited thereto. In these Examples, all percentages and parts are givenby weight unless otherwise specified. Example 1 The preparation ofCatalyst A Into a mixture of 100 parts of industrial trichlorobenzene,parts of aluminum powder (100 mesh) and a minute amount of aluminumchloride kept at 100 C was introduced hydrogen chloride gas withstirring. After 6 hours, the aluminum was consumed completely, wherebyaluminum chloride was obtained in the form of a uniform dispersion inthe trichlorobenzene.

Yield of aluminum chloride-over 98% Absorption ratio of hydrogenchlorideover 97% Example 2 The preparation of Catalyst B After mixing 28parts of 1,2,4-trichlorobenzene with l part of aluminum powder and aminute amount of aluminum chloride at 150 C, hydrogen chloride wasintroduced into the mixture. The reaction proceeded exothermically andwas completed almost quantitatively with regard to the hydrogenchloride. A slightly yellowish dispersion of aluminum chloride was ob-"tained. The dispersion was filtered rapidlyand the re: sultant crystalswere washed with anhydrous ben'ie'ne and dried. The analytical values ofthe product were "as followszf Aluminum 20.0% (Calculated value 20.2%)Chlorine 80.4% (Calculated value 79.8%) Example 3 The preparation ofCatalyst granules, sand-like particles and small blocks are'use Aftermixing 200 parts of industrial trichlorobenzene containing less than0.1% of water, with 11 parts of sand-like aluminum and a minute amountof aluminum chloride at C, hydrogen chloride gas was introduced into themixture. After the reaction fw a's completed, the obtained crystals werefiltered at 20 C and washed with anhydrous benzene and dried. The yieldwas 98.6%.

The analytical values of the product were as follows:

Aluminum 20.8%

Chlorine 79.1%

Example 4 To a mixture of 70 moles of benzene and 2.10 moles (asaluminum) of the dispersion of Catalyst A was added 1.0 mole of phthalicanhydride in 1 hour at 30 C. Aftr being maintained at that temperaturefor 1 hour, the mixture was heated at 70 C for 2 hours.

The reaction mixture was poured into an aqueous diluted hydrochloricacid solution, and the organic layer was separated under heating, andthen steam-distilled. The thus obtained residual crystal was filteredoff and dried.

o-Benzoylbenzoic acid was obtained with a 97.8% purity in a 96% yield.

When conventional aluminum chloride was used, 2.20 moles (as aluminum)of aluminum chloride was required and 5 hours heating at. 70 C wasneeded to obtain the same result.

Example 5 The same procedure as in Example 4 was repeated except thatthe aluminum chloride suspension was replaced by aluminum chlorideobtained by filtering said suspension under nitrogen stream and washingwith benzene, to obtain the same result. Since the reaction productafter hydrolysis consisted solely of the desired product and benzene,o-benzoylbenzoic acid was obtained by simply separating the benzenetherefrom by distillation.

Example 6 To a mixture of 5.0 moles of monochlorobenzene and 2.10 moles(as aluminum) of the dispersion of Catalyst A, was added 1.0 mole ofphthalic anhydride in 1 hour at 30 C. After being maintained at thattemperature for 1 hour, the mixture was heated at 85 C for 3 hours.

The resulting mixture was treated as in Example 1 to obtain4'-chloro-o-benzoylbenzoic acid in a 93% yield.

When conventional aluminum chloride was used, 5 hours heating at 8085 Cwas needed to obtain the same result.

Example 7 To 2.3 moles (as aluminum) of a dispersion of Catalyst A wasadded 1.0 mole of phthalic anhydride and the resulting mixture wasstirred at 10 C. After adding 4.0 moles of ethylbenzene dropwise below10 C, the resultant mixture was maintained at that temperature for 2hours and then heated at 40 C for 1 hour.

After-treated according to an ordinary process, was obtained4-ethyl-o-benzoylbenzoic acid, having a melting point of 120l21 C in ayield.

Other monoor dialkyl substituted o-benzoylbenzoic acids were obtained bya similar procedure to the above in high purity and high yield.

What is claimed is:

1. A process for the production of active anhydrous aluminum chloride,which comprises reacting metallic aluminum with anhydrous hydrogenchloride using at least one member of trichlorobenzenes as a solvent inan amount of five to 30 times the weightof the aluminurn used at atemperature of from 30 to 200 C.

2.'"A p'r'ocess according to claim 1, wherein the reacsome startd in thepresence of a minute amount of aluminum chloride.

2. A process according to claim 1, wherein the reaction is started inthe presence of a minute amount of aluminum chloride.